High temperature alloys



Deformation Rodions hr.

Shess L0 3.0 5.0 7.0 9.0 I10 130 I50 M. N. ORNITZ E HIGH TEMPERATURE ALLOYS Oct. 1, 1968 3,403,998

Filed Feb. 5, 1965 Fig.l. Fi .2.

Fi .3. Fig.4.

in C .Ol6 .9 .0004

3 I! .Ol2 l .0003

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INVENTORS Martin N. Ornitz 8 Roy H. English Temp. "F

United States Patent Oflice 3,403,998 Patented Oct. 1, 1968 3,403,998 HIGH TEMPERATURE ALLOYS Martin N. Ornitz, Wilkinsburg, and Ray H. English, Mc-

Candless Township, Allegheny County, Pa., assignors to Blaw-Knox Company, Pittsburgh, Pa., a corporation of Delaware Filed Feb. 5, 1965, Ser. No. 430,544 3 Claims. (Cl. 75-171) ABSTRACT OF THE DISCLOSURE This invention relates to high temperature alloys and more particularly to an alloy and parts made therefrom having high strength and low creep at temperatures up to 2500 F. coupled with resistance to corrosion and thermal shock. The need for alloys having high strength and low creep, coupled with resistance to corrosion and thermal shock in the temperature range of 2400 F., has long been recognized. Such alloys are particularly desirable instead of ceramic refractories and the like in rollertype furnaces and slab heaters as well as in radiant heat tubes and the like which are openated in the temperature range of 2400 F. Conventional alloys used for applications in this temperature range have not been satisfactory for most uses because of the high rate of creep, corrosion and lack of strength at temperatures at or about 2200 F. to 2500 F.

We have discovered an alloy composition having high strength and low creep characteristics coupled with corrosion resistance and high resistance to thermal shock at temperatures up to 2500 F. The surprising characteristics of this alloy appear to be particularly dependent upon the control of carbon, iron and tungsten within a critical nickel-chromium base analysis. The broad composition range of the alloy of this invention lies within the following limits:

C Up to about 1.0%. Cr About 26% to about 38%.

W About to about 25%.

Mn About 0.2% maximum.

Si About 0.2% maximum.

Ni Balance with usual impurities in ordinary amounts.

Percent (about) C 0.20.75 Cr 28-35 W 13-19 Ni 40-60 A single preferred composition would be:

'if the desired high strength,

Percent (about) C 0.5 Cr 31 Ni 51 W 17 With balance impurities in ordinary amounts We have found that the above ranges must be observed low creep corrosion resistance and resistance to thermal shock at the higher temperatures here contemplated are to be achieved. We have found that as the temperature of service increases, the carbon content should preferably be on the low end of the stated carbon range and that the manganese and silicon should be low as should the usual impurities associated with nickel',"such as iron.

The unusual properties of our alloy and the criticality of the composition are perhaps best illustrated by comparison of the following test results and examples.

Example I A group of alloys were melted to evaluate the effectiveness of various combinations within the broad range of the invention in creep control at 2400 F. The alloys were formed and tested at 2400 F. in a standard cantilever creep test using 250 lb./in. loading with the following results:

TABLE 1 Analysis, Percent Rate of Creep,

rad/hr. Ni Cr C W 48. 2 37. 1 02 9. 95 00021 49. 0 31. 7 02 14. 44 000138 45. 0 34. 3 02 13. 77 00035 47. 7 33. 7 27 14. 38 00021 48. 5 33. 0 41 14. 11 00011 48. 4 33. 3 52 14. 52. 0001 48. 1 33. 67 14. 76 00002 48. 0 33. 5 1. 01 14. 20 00023 47. 8 33. 3 59 14. 35 0004 47. 5 29. 1 59 18. 75 00012 47. 7 24. 2 61 24. 16 00046 47. 3 19. 2 56 29. 67 rapid 51. 5 28. 7 57 14. 82 0017 57. 4 24. 5 61 14. 17 rapid 46. 8 29. 5 01 19. 4 00011 47. 7 29. 8 31 17. 2 00018 48. 4 30. 0 01 19. 92 0054 48. 8 30. 5 04 18. 8 0012 47. 7 30. 8 10 19. 4 0027 49. 6 30. 4 15 19. 12 00123 47. 9 30. 3 19 20. 2 00067 48. 5 30. -7 31 18. 8 0048 48. 2 29. 9 37 19. 4 00088 59. 1 29. 9 38 9. 12 0200 55. 5 29. 7 37 13. 6 0040 52. 8 28. 9 40 14. 8 0025 50. 7 28. 6 41 17. 36 0026 49. 0 30. 1 40 19. 76 0047 47. 4 29. 6 40 20. 96 0051 45. 7 29. 0 40 22. 72 0180 53. 5 31. 8 05 14. 7 00037 55. 1 30. 6 04 15. 4 0027 52. 7 30. 8 03 16. 4 0017 53. 0 31. 1 05 17. 6 0027 50. 0 30. 7 01 17. 3 00053 This data is plotted in FIGURE 1.

Example II A series of alloys were melted at the 14% tungsten level with various carbon contents to determine the effect of carbon. The results are plotted in FIGURE 2.

Example III A series of alloys at 0.6% carbon and at 0.4% carbon with varying tungsten were made. The chromium content was 30% and the nickel varied with tungsten to produce a nickel and tungsten content of in FIGURE 3. In

FIGURE'4 the nickel content was maintained at 48% and the chromium varied with tungsten to produce a chrmium and tungsten content of 50%.

Example IV Stress rupture data were determined on several alloys Whose analyses were as follows:

TABLE 2(A) 0 Mn Si Ni Cr W 01 .02 06 47. 30. 7 20. 0 05 01 06 40. 5 30. 6 19. 8 ()1 01 07 50. 0 28. 6 20. 0 O1 01 02 49. 8 28. 2 20. 0 01 02 18 47. 7 30. 7 19. 8 38 02 02 48. 5 29. 5 20. 0 66 02 .10 46.1 27. 3 20. 5 48 02 04 32. 3 49. 0 16. 4 23 01 01 44. 6 31. 7 10. 0 38 02 02 48. 5 29. 5 20. 0 31 01 .01 45. 8 31. 6 19.0 41 O1 01 45. 8 31. 7 19. 0 01 O1 45. 8 31. 6 19. O

The stress rupture data are set out in the following table:

TABLE 2(B) 0 Stress Rate Time to Rupture 38 5, 000 0092 350 35 4, 000 0046 850 45 4, 000 0044 825 10 4, 000 330 v 3, 000 0000 1 1, 685 1 N o fracture.

The foregoing stress rupture characteristics are shown in FIGURE 5.

The foregoing tables and accompanying drawings clearly illustrate the criticality of the composition of this al- 10y and the very significantly improved creep resistant properties.

While we have described certain preferred embodiments of our invention in the foregoing specification, it will be understood that the invention may be otherwise embodied within the scope of the following claims.

We claim:

1. A low creep, high strength alloy resistant to corrosion and thermal shock at temperatures up to 2500 F. consisting essentially of an etfective amount upto about 1.0% carbon to provide high strength, corrosion resistance and low creep at elevated temperatures, about 26% to 38% chromium, up to about 0.2% manganese, up to about 0.2% silicon, about 10% to 25% tungsten and the balance nickel with residual impurities in ordinary amounts.

2. A low creep, high strength alloy resistant to corrosion and thermal shock at temperatures up to 2500 F. consisting essentially of about 0.20% to 0.75% carbon, about 28% to 35% chormium, up to about 0.2% manganese, up to about 0.2% silicon, about 13% to 19% tungsten and the balance nickel with residual impurities in ordinary amounts.

3. A low creep, high strength alloy resistant to corrosion and thermal shock at temperatures up to 2500 F. consisting essentially of about 0.5% carbon, about 31% chromium, about 17% tungsten and the balance nickel with residual impurities in ordinary amounts.

References Cited UNITED STATES PATENTS 1,774,862 9/1930 Wissler l71 2,396,552 3/1946 Cape 75-171 2,458,502 l/1949 Cape 75171 RICHARD O. DEAN, Primary Examiner. HYLAND BIZOT, Assistant Examiner. 

